The Impact of Metabolomics on Flavor Chemistry Josephine Charve and Gary Reineccius Department of Food Science and Nutrition University of Minnesota.

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Presentation on theme: "The Impact of Metabolomics on Flavor Chemistry Josephine Charve and Gary Reineccius Department of Food Science and Nutrition University of Minnesota."— Presentation transcript:

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The Impact of Metabolomics on Flavor Chemistry Josephine Charve and Gary Reineccius Department of Food Science and Nutrition University of Minnesota

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Flavoromics My definition - The application of chemometrics to the study of a broad array of chemical stimuli involved in forming human flavor perception. My definition - The application of chemometrics to the study of a broad array of chemical stimuli involved in forming human flavor perception.

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Historically – volatiles were the primary interest of the flavor chemist

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Why now? Developments in “omics” are driving the development (and availability) of instrumentation, approaches, and data handling and analysis. Developments in “omics” are driving the development (and availability) of instrumentation, approaches, and data handling and analysis. Our University Our University Two new metabolomics faculty Two new metabolomics faculty Over $2,000,000 in advanced MS and some nmr instrumentation Over $2,000,000 in advanced MS and some nmr instrumentation Staffing with data handling/analysis experts from Super Computing Center Staffing with data handling/analysis experts from Super Computing Center

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Preparation/Isolation Volatiles – not much help. Volatiles – not much help. We recognize the limitations of any extraction/isolation method We recognize the limitations of any extraction/isolation method Help with instrumentation for volatiles Help with instrumentation for volatiles

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Non-volatiles – helping us Searching for “best” method for us. Searching for “best” method for us. Going through a host of methods evaluating each for sensitivity and breath Going through a host of methods evaluating each for sensitivity and breath

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Non-volatiles – common approach Solvent extraction of solid tissues Solvent extraction of solid tissues Mechanical disruption of the tissue (grinding, vibration or other methods on a frozen sample.) Mechanical disruption of the tissue (grinding, vibration or other methods on a frozen sample.) Solvent selection varies widely with compounds of interest; Solvent selection varies widely with compounds of interest; polar compounds being best extracted with isopropanol, ethanol, methanol, acidic methanol, acetonitrile, water, and methanol:water. polar compounds being best extracted with isopropanol, ethanol, methanol, acidic methanol, acetonitrile, water, and methanol:water. Non-polar compounds are most often extracted with chloroform or ethyl acetate Non-polar compounds are most often extracted with chloroform or ethyl acetate (Dettmer et al., 2007). (Dettmer et al., 2007).

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Analysis MS –GC/GC, LC (UPLC), direct analysis MS –GC/GC, LC (UPLC), direct analysis Long history of application of basic techniques to foods Long history of application of basic techniques to foods Impressive evolution in methods Impressive evolution in methods nmr nmr Applied to foods in related work for more than two decades. Applied to foods in related work for more than two decades. Historically, emphasis was to detect adulteration and fraud Historically, emphasis was to detect adulteration and fraud

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Ambient ionization – gas analysis PTR-MS or API-MS PTR-MS or API-MS Ideally suited to providing an ion profile of a gaseous sample Ideally suited to providing an ion profile of a gaseous sample Many current applications in flavor chemistry Many current applications in flavor chemistry

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nmr MS offers sensitivity and capacity to detect compounds in mixtures but are limited to ionizable species, have difficulties resolving isomers, and usually require standard compounds for quantification. NMR has the capacity to characterize chemical structure and quantity but is limited to the most abundant compounds in a given sample without isotope labeling. (several other limitations) Quantitative and reproducible – statistical analysis Sensitivity not limited by same factors as MS High throughput – 500 samples per day (Pan and Raftery, 2007; (Lindon et al., 2004 Hegeman et al. Anal. Chem. 2007, 79, , Hegeman for isotope labeling studies; (Pan and Raftery, 2007; (Lindon et al., 2004

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MetAlign TM Used in numerous publications for data extraction from GC-MS and LC-MS data sets. Used in numerous publications for data extraction from GC-MS and LC-MS data sets. Pulls out all of the masses and sorts which are the same in all of the data sets and which could differentiate the data. Pulls out all of the masses and sorts which are the same in all of the data sets and which could differentiate the data. Allows the user to look for unique peaks in the sample set above a chosen noise threshold Allows the user to look for unique peaks in the sample set above a chosen noise threshold (Lomen et al., 2006). (Lomen et al., 2006).

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MetAlign “MetAlign is a software program for full scan LC-MS and GC-MS comparisons and was designed and written by Arjen Lommen of RIKILT-Institute of Food Safety. It has been extensively tested in collaboration with Plant Research International.” “MetAlign is a software program for full scan LC-MS and GC-MS comparisons and was designed and written by Arjen Lommen of RIKILT-Institute of Food Safety. It has been extensively tested in collaboration with Plant Research International.”

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Result total of 5,250 unique 12C masses were obtained from extracts of the four different developmental fruit stages, ionized in the four ionization modes. total of 5,250 unique 12C masses were obtained from extracts of the four different developmental fruit stages, ionized in the four ionization modes. In the red stage extract, 55% of the masses were assigned a single empirical formula, 10% two formulae, and 35% three or more formulae. In the red stage extract, 55% of the masses were assigned a single empirical formula, 10% two formulae, and 35% three or more formulae. Went to data databases for help - 159,000 natural products (Chapman and Hall, Dictionary of Natural Products) Went to data databases for help - 159,000 natural products (Chapman and Hall, Dictionary of Natural Products)

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Next steps Look for changes or relationships of data to some attribute via multivariate statistics Look for changes or relationships of data to some attribute via multivariate statistics Identify the compounds of interest. Identify the compounds of interest. HPLC, mass spectrometry (MS/MS) and/or nuclear magnetic resonance (NMR) must be employed. HPLC, mass spectrometry (MS/MS) and/or nuclear magnetic resonance (NMR) must be employed. Evaluate result for value Evaluate result for value